Deck 5: IEEE 80211 Media Access Control and Network Layer Standards

Question 1

A BSS is ____.

A) a group of wireless devices that is served by a single access point
B) a unique identifier
C) a geographical area where wireless devices reside
D) two or more networks that are connected through a common distribution system

Answer 1

A

Question 2

On ESS networks that have multiple access points, the wireless device might actually receive beacon frames from several APs. Which AP would a wireless device generally choose in this case?

A) the closest
B) the one with the fewest wireless devices attached to the AP
C) the one with the strongest signal strength
D) the choice will be random

Answer 2

C

Question 3

Following authentication, if the access point accepts the wireless device, it reserves memory space in the AP and establishes a(n) ____ ID for it.

A) association
B) device
C) member
D) authentication

Answer 3

A

Question 4

What is the default authentication method according to the 802.11 standard?

A) basic
B) open system
C) shared key
D) private key

Question 5

What is the minimum number of BSS networks required to form an ESS?

A) 0
B) 1
C) 2
D) 10

Question 6

All frames contain the MAC address of the source and destination device, a frame sequence number, and a frame ____ used for error detection.

A) unit
B) flag
C) sum
D) check sequence

Question 7

The ____ field appears last in a data frame.

A) Frame control
B) Duration
C) Sequence control
D) Frame check sequence

Question 8

When an ESS is installed it is desirable to configure the areas of coverage much like cells in a cellular telephone system.

Question 9

The ____ field appears first in a management frame.

A) Frame control
B) Duration
C) Destination address
D) BSSID

Question 10

The first major function of the MAC layer involves defining procedures for a wireless device to discover the WLAN.

Question 11

CSMA/CA eliminates the possibility of collisions.

Question 12

Which of the following describes a wireless device switching from one AP to another?

A) roaming
B) handoff
C) routing
D) redirecting

Question 13

A home agent is a forwarding mechanism that keeps track of where the mobile computer is located.

Question 14

When an AP accepts or rejects a wireless device it sends a(n) ____ frame.

A) association request
B) association response
C) disassociation
D) reassociation

Question 15

Why is CSMA/CD unsuitable for wireless networks?

A) Hidden node problem
B) difficult to detect collisions
C) difficult to synchronize backoff times
D) Both A and B

Question 16

What is the first step in shared key authentication?

A) AP encrypts challenge text and sends it to wireless device
B) wireless device encrypts challenge text and sends it to AP
C) AP sends wireless device an authentication frame that contains a block of text known as the challenge text
D) wireless device sends an authentication frame to the AP

Question 17

In an infrastructure network the beacon interval is normally set to ____ ms, although it can be modified.

A) 1
B) 10
C) 100
D) 1000

Question 18

What is the difference between passive and active scanning?

A) which device initiates the discovery
B) the speed at which discovery is made
C) the number of devices that can be supported
D) the security of the network

Question 19

Wireless authentication involves a user logging on to the access point.

Question 20

At regular intervals the AP in an infrastructure network or wireless device in an ad hoc network sends a ____ frame both to announce its presence and to provide the necessary information for other devices to join the network.

A) master
B) beacon
C) data
D) control

Question 21

What is a Basic Service Set?

Question 22

Describe the three interframe spaces (IFS) defined in the 802.11 standard.

Question 23

How does open system authentication work?

Question 24

What is a management frame? What are the fields in this type of frame?

Question 25

With MobileIP, the ____ assigns the mobile computer a new (but temporary) IP number.

A) local AP
B) foreign AP
C) foreign agent
D) roamed network

Question 26

____________________ involves dividing the data to be transmitted from one large frame into several smaller ones.

Question 27

____ effectively prevents collisions because every device must wait until it receives permission before it can transmit.

A) CSMA/CD
B) CSMA/CA
C) Polling
D) Fragmentation

Question 28

Describe power management for an ad hoc configuration.

Question 29

When a laptop, either in ad hoc or infrastructure mode, is connected to a standard alternating current (AC) plug for power it is in ____________________ mode and remains in communication with the AP or other wireless devices.

Question 30

CSMA/CA reduces collisions is by using explicit frame acknowledgment. Describe how frame acknowledgment works.

Question 31

What fields are contained in the body of a beacon frame?

Question 32

The ____ draft defines a superset of features that is intended to provide QoS over WLANs.

A) 802.11a
B) 802.11b
C) 802.11e
D) 802.11g

Question 33

Wi-Fi Multimedia (WMM) outlines four levels of prioritization for WLAN QoS. Name and provide a brief description for each one.

Question 34

____________________ IP provides a mechanism within the TCP/IP protocol to support mobile computing by using a home agent as a forwarding mechanism to keep track of where the mobile computer is located.

Question 35

The 802.11 standard provides an option that can be used when collisions occur due to a hidden node. That option is known as ____.

A) virtual node detection
B) node collision protocol
C) virtual carrier sensing
D) hidden node detection

Question 36

A wireless device sends an authentication frame to the AP. The AP sends back an authentication frame that contains a block of text known as the ____________________.

Question 37

A(n) ____________________ Service Set is a wireless network that does not use an access point.

Question 38

The RTS/CTS protocol is especially taxing when ____ data packets are being transmitted.

A) short
B) long
C) encrypted
D) redirecting

Question 39

An access point sends out a beacon frame containing a ____ identifying the stations that have buffered frames waiting at the access point.

A) buffer list
B) traffic indication map
C) waiting map
D) buffered cache

Question 40

Describe Mobile IP.

Question 41

Describe IP addresses and explain how they are allocated and used.